032
FXUS63 KFSD 151128
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
628 AM CDT TUE APR 15 2025
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES AND PERIODIC BREEZY CONDITIONS
EXPECTED THROUGH MID WEEK.
- SHOWERS AND THUNDERSTORMS RETURN TO THE FORECAST BY THURSDAY
AND CONTINUE INTO FRIDAY. CONDITIONAL RISKS FOR SEVERE WEATHER
REMAIN ON THURSDAY, SO CONTINUE TO MONITOR THE FORECAST.
- SLIGHTLY COOLER TEMPERATURES INTO THE WEEKEND, WITH INCREASING
RISK FOR RAIN RETURNING BY SUNDAY MORNING. CHANCES CONTINUE
INTO EARLY NEXT WEEK, ALTHOUGH DETAILS ARE STILL UNCERTAIN.
DISCUSSION
ISSUED AT 402 AM CDT TUE APR 15 2025
NOW-WEDNESDAY NIGHT: CLEAR SKIES AND BREEZY NORTHWESTERLY WINDS
CONTINUE THIS MORNING GUSTING TO 20-25 MPH AT TIMES. TEMPERATURES
ARE IN THE UPPER 20S TO MID 30S, BUT WIND CHILLS ARE IN TEENS TO MID
20S.
SURFACE HIGH PRESSURE SLIDES INTO THE AREA THIS AFTERNOON AND
EVENING, WHICH SHOULD ALLOW FOR WINDS TO TAPER OFF AS WE HEAD
THROUGH THE LATE AFTERNOON. HOWEVER, EXPECT GUSTS AROUND 25 MPH TO
CONTINUE INTO THE EARLY EVENING EAST OF I-29. WINDS ALSO SHIFT
SOUTHERLY THROUGH THE AFTERNOON AND EVENING FROM WEST TO EAST. THIS,
ALONG WITH WAA AND RIDGING ALOFT BUILDING TO THE WEST, WILL ALLOW
FOR A SLIGHTLY WARMER DAY WITH HIGHS IN THE UPPER 50S TO MID 60S.
DRY AIR ALLOWS RH VALUES TO DROP BELOW 25% FOR MUCH OF THE AREA, BUT
LIGHTER WINDS COINCIDENT WITH LOWEST RH VALUES TEMPERS FIRE CONCERNS
FOR TODAY. LOWS TONIGHT FALL TO THE MID 30S TO LOWER 40S.
SURFACE HIGH SLIDES EAST WEDNESDAY, WITH MID AND UPPER LEVEL RIDGING
SLIDING EAST AS WELL. CONTINUED WAA AND SOUTHEASTERLY LOW LEVEL FLOW
LEAD TO ANOTHER WARM DAY WITH HIGHS IN THE 70S. SOUTHEAST WINDS
BECOME BREEZY DURING THE AFTERNOON, MAINLY ALONG AND EAST OF I-29,
WITH MIXING AND TIGHTENING SPG. INCREASING MOISTURE KEEPS RH VALUES
IN THE 25-30% RANGE, SO ANTICIPATE ELEVATED FIRE DANGER ON
WEDNESDAY. WEDNESDAY NIGHT REMAINS MILD, WITH LOWS IN THE UPPER 40S
AND LOWER 50S.
THURSDAY: BY EARLY THURSDAY MORNING, THE FIRST SHORT
WAVE/DISTURBANCE MOVES INTO THE MO RIVER VALLEY AS MID AND UPPER
LEVEL LONG WAVE TROUGHING DEEPENS TO THE WEST. SIMULTANEOUSLY,
SURFACE LOW PRESSURE BEGINS TO WORK ITS WAY EAST OUT OF THE ROCKIES
AND A WARM FRONT LIFTS INTO NORTHERN SD. SOUNDINGS INDICATE A VERY
STRONG CAP ACROSS MUCH OF THE AREA THROUGH THE LATE OVERNIGHT HOURS
WEDNESDAY INTO DAYBREAK THURSDAY. HOWEVER, IF AN ELEVATED STORM CAN
DEVELOP AT OR NEAR THE 850:700 MB LEVEL NEAR THE FRONT, IT MAY HAVE
ABOUT 1000 J/KG OF MUCAPE TO WORK WITH, ALONG WITH MID LEVEL LAPSE
RATES OF ALMOST 8 DEG C/KM. IF A STORM CAN DEVELOP, HAIL TO QUARTER
SIZE (1") IS POSSIBLE.
ATTENTION TURNS TO THE AFTERNOON HOURS AS THE TROUGH MOVES EAST AND
ANOTHER MID LEVEL SHORTWAVE (OR TWO) MOVE THROUGH. GUIDANCE IS STILL
A BIT UNCERTAIN IN A FEW ITEMS: IF A SURFACE LOW DEVELOPS OVER
EASTERN NE, WHAT TIME THE SURFACE COLD FRONT MOVES THROUGH, AND
WHERE/HOW ROBUST THE EML IS. REGARDLESS OF THESE, WE'LL SEE
INCREASING MOISTURE AND INSTABILITY WITH SOUTH-SOUTHEASTERLY FLOW
AHEAD OF THE FRONT. SHOWERS AND THUNDERSTORMS CONTINUE THROUGH THE
DAY AND EVENING, WITH SOME DURING THE AFTERNOON/EVENING POSSIBLY
BECOMING STRONG TO SEVERE AFTER 2 PM. THE GREATEST RISK REMAINS
ACROSS NORTHWESTERN IA BACK TO THE WEST INTO FAR SOUTHEASTERN SD AND
NORTHEASTERN NE - ALTHOUGH STRONG TO SEVERE RISK EXISTS AS FAR WEST
AS THE JAMES RIVER VALLEY (AGAIN, TIMING DEPENDENT). MUCAPE VALUES
EXCEED 1200 J/KG AND WITH LAPSE RATES STILL OVER 7.5 DEG/C KM AND
SHEAR INCREASING INTO THE EVENING, EXPECT LARGE HAIL TO BE THE MAIN
THREAT (HALF DOLLAR SIZE) WITH WIND GUSTS OF 60 MPH POSSIBLE AS
WELL. IF THE WARM FRONT REMAINS/DROPS FURTHER SOUTH AND A STORM IS
SURFACE BASED, CAN'T ENTIRELY RULE OUT THE POSSIBILITY OF A TORNADO
ACROSS THE EASTERN PORTIONS OF THE AREA.
FRIDAY: BEHIND THE COLD FRONT, BREEZY NORTHWESTERLY WINDS
CONTINUE INTO FRIDAY. COOLER WITH HIGHS IN THE 50S.
SATURDAY-TUESDAY: MID AND UPPER LEVEL POSITIVELY TILTED TROUGH
REMAINS IN PLACE INTO THE EARLY PART OF THE WEEKEND, WITH LOW
PRESSURE CLOSING OFF ACROSS THE FOUR CORNERS REGION OF THE US. THIS
MOVES NORTH DURING THE WEEKEND, WITH CONTINUED SHORT WAVES INTO THE
EARLY PART OF NEXT WEEK. RAIN CHANCES WILL BE DEPENDENT ON THE TRACK
OF EACH SYSTEM, WHICH GUIDANCE REMAINS QUITE VARIED ON. GENERALLY
EXPECT PERIODIC PRECIP CHANCES AND BREEZINESS WITH NEAR NORMAL
TEMPERATURES.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 627 AM CDT TUE APR 15 2025
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. WINDS MAY GUST
AROUND 20 KNOTS AT TIMES, ESPECIALLY ALONG AND EAST OF I-29.
EXPECT WINDS TO SHIFT DIRECTION MULTIPLE TIMES THROUGH WEDNESDAY
MORNING.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...SG
AVIATION...SG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page